Fire control system



June 26, 1951 E. M. DELORAINE FIRE cou'mor. svsma s Sheets-Sheet 1 ORNEY Filed Aug. 22, 1942 INVENTOR EDMOND M. 05mm J1me 1951 E. M. DEILORAINE 2,

FIRE CONTROL SYSTEM Filed Aug. 22, 1942 3 Sheets-Sheet 2 INVENTOR EDMOND M. DELOMINE 72 f ATTORNEY Jul!!! 1951 E. M. DELORAINE 2,557,949

' FIRE con-mm. svs'rsu Filed Aug. 22, 1942 '3 Sheets-Sheet 3 VOLTAGE 50 IEO DlsTANCE IN MILES a 4 22 s o DISTANCE IN MILES INVENTOR EDMOND M DELORAINE Fatented June 26, 1951 FIRE CONTROL SYSTEM Edmond M. Deloraine, New York, N. Y., assigncr to Federal Telephone and Radio Corporation,

a corporation of Delaware Application August 22, 1942, Serlal 455,785 9 Claims. (01. 89-41) This invention relates to fire control systems and more particularly'to a. system for detecting the positions of moving obstacles such as enemy aircraft and projectiles or shells fired toward the aircraft, and causing the shells to'burst in the immediate vicinity of the aircraft.

In firing upon moving targets such as aircraft, one must, in addition to the necessity of predieting theproper azimuth and elevation of the gun forming a shell at a given time, also predict the range at which the shell is to explode in order to adjust properly the time fuse" of the shell. 1

It obvious that the azimuth and elevation of the gun must be set at the time the shell is fired, but one can expect to improve the accuracy of timing of the fuse by ca y g out the operation by remote control means only as the shell is nearing the target. By this-method it is not necessary to predict any more the range at which the shell is to explode i. e. the setting of the time fuse.. The predictor equipment is thereby simplified and the time of bursting of the shell can be made more accurate as such elements as variable velocity of-the shell are thereby eliminated.

One object of the invention therefore is to simplify the predictor equipment used with the gun and to increase the accuracy of the shell detonation with respect to fast moving targets.

Another object of this invention is to provide a firing control system using electro-magnetic impulses to detect moving obstacles such as aircraft and detonatable projectiles in flight, and by which an operator can by varying the transmission of the impulses from a detection character to a detonation character determine the detonationposition of the projectile after it has commenced its flight.

Another object of this invention'is to provide a system and method for detecting enemy aircraft, directing the firing of shells'in accordance with the position-and movement of the aircraft and determining the detonationtiming of the shell during its flight so that itmay be caused to burst the instant it reaches the vicinity of the aircraft. I o I Another object of this invention is to provide a firing control system and method for timing the detonation of a fired shell during its flight, that is to say, determining the detonation timing of the shell after the firing thereof and at some point in" its flight, preferably as it nears the target.

Another object of this invention is to-provide a detonatable shell capable of being detonated by remote control while the shell is in flight.

Another object of this invention is to provide a shell which is responsive to detonating impulses only after the shell has reached a predetermined distance away from the gun.

Still another object of this invention is to provide a shell having an arming fuse adapted to increase the impulse refiecting capacity of the shell after the shell has been in flight a predetermined interval of time so that it may thereafter be more observable on obstacle detection apparatus.

An additional object of this invention is to provide a control system for normal transmission of radio pulses for detection purposes and which can be controlled to greatly increase the Irequency of the pulses to increase the energy transmitted thereby for a given interval of time.

The above objects and others ancillary thereto will become mor apparent upon consideration of the following detailed description to be read in connection with the accompanying drawings, in which,

Fig. l is a schematic illustration of a firing control system and an anti-aircraft gun in accordance with this invention Fig. 2 is a cross-sectional view of a portion of a shell embodying arming and detonation features of this invention;

Fig. 3 is a schematic illustration of the shell and a detonation circuit therefor with an arming antenna shown in arming Position;

Fig. 4 is a schematic illustration of a form of arming circuit that may be used in connection with the arming antenna shown in Figs. 2 and 3;

Fig. 5 is a modified form of an arming and detonation circuit arrangement;

Fig. 6 is a graph indicating the detpnating voltage build-up in the circuits shown in Figs. 3

and 5;

Figs. 7 and 8 are views in elevation of an oscillograph showing aircraft and shell reflection indications;

Fig. 9 is a schematic illustration of a semiautomatic control device adapted to control the transmission of shell detonation impulses; and

3 Fig. 10 is a modified form of control means for switching from obstacle detection impulses to shell detonation impulses.

Referring to Fig. 1 of the drawings, an antiaircraft system constructed in accordance with this invention is shown firing at an enemy airplane. The system includes a known obstacle detection device adapted to detect and indicate the distance and location of obstacles, such as aircraft and ships, by means of electromagnetic wavesor impulses. One type of such'device is shown in patent to Lyman 2,231,929, February 18, 1941. The device [0 isshown diagrammatically, it being understood that the lines connecting different parts may comprise one or more wires;

The obstacle detection device l0 comprises a transmitting antenna l2 and a plurality of receiving antennae ll, 15 and l6, l1 the directivity of which can be adjusted so as to permit. on the one hand, a'scanning lookout over a great range and, on the other hand, the exact measurement of geometrical co-ordinants for gun fire purposes such as distance, azimuth and elevation. The

antenna I2 is connected to a suitable transmitter T which is provided with a source E of carrier energy and impulse generators FI- andF2 controlled by a switc de vice S. The impulse generator Fl is norm connected by the switch S to the transmitter T for the purpose of transmitting radio impulses at a frequency such as 60 cycles per second for obstacle detection purposes.

. 4 I moved horizontally about a vertical supporting shaft 40 driven by a motor ll under control of a variable speed control device 42. For precise manipulation of the antenna systcm'as when an obstacle is indicated by a pulse onthe panoramic oscillograph, the control motor isde-energized and the antennae system is than controlled man- Y ually by elevation and azimuth control-wheels 44 The impulse generator F2 provides impulses at a I greatly increased frequency such as at the rate of 30,000 per second and are used only when the switching device is actuated for the purpose of transmitting shell detonating impulses. The energy supply source E is, of course, such as to provide a large power supply satisfactory for the transmission of the high frequency pulses produced by the generator F2.

For the purpose of detecting pulse reflections caused by aircraft or other obstacles in response to transmitted impulses, a receiver R. is connected to the antennae I4, l5 and l6, H. The receiver B. may be of any known type capable of indicating in response to pulses received by the two sets of antennae, the elevation and azimuth of a se lected obstacle. Associated with the receiver R is an oscillograph to enable operators to efiect precise measurements of azimuth, elevation, and distance with respect to a detected airplane. These measurements are transmitted continuously to the gun firing control station such as an anti-aircraft gun for automatic control of the firing position of the gun. The gun, of course, may be operated manually instead of automatically in accordance with measurement indications transmitted thereto from the obstacle detecting device. In order to provide a reference point 22 by which to follow the reflection pulse of an airplane 3| and thereby provide distance indication for the gun 25, a suitable time base control 32 is provided. The output of the time base control 32 is fed to a cathode ray tube providing the oscillograph 20 and to the gun station as indicated by the lines 34 and 35. The oscillograph 20, is of course, provided with the usual saw-tooth wave generator SG. It will also be understood that a suitable blocking means B is disposed between the transmitter T and the receiver B so that the receiver will be blocked during the transmission of shell detonation impulses.

For lookout scanning, the antennae may be gun station 25, the travel of the shells toward the.

aircraft can likewise be followedon the same 05- cillograph. As the reflection pulse indication 50?.

of a shell 5| reaches a position or; the oscillograph coinciding or nearly coinciding with the...

reflection pulse 30 of the aircraft, the operator may then actuate a switch 49 causing the switch S to switch over the transmitter T from the im-g; pulse generator Fl to the impulse generator F2. This instantly increases the impulse transmis-vs sion to say, 30,000 cycles per second thereby -in-' creasing greatly the average energy of the trans: mitted pulses so as to set off the detonation fuse of the shell. For example, where the obstacle detection pulses are transmitted at 60 per second, the increase to 30,000 per secondgives 2,000 times as much energy during the interval of a sixtieth of a second. The manual actuation of the switch 49 may be varied and the detonation of the shells observed so that successive shell detonations can be caused to occur in various points in the homediatevicinity of the plane.

The gun 25 is preferably of the type capable of firing shells in rapid succession of about one per second. The shells fired by the gun 25 are provided with a detonation fuse which is responsive to detonation impulses transmitted by the detection apparatus. These shells as shown more particularly in Figs. 2, 3 and 4 comprise a body 52 containing a charge of explosive powder 53 and an end compartment containing a detonation fuse controlling circuit 55 having a fuse 56 extending into the explosive charge; The circuit 55 includes a condenser 50 and a gas filled discharge tube 60. The condenser 52 is charged to a predetermined voltage prior to the firing or after firing of the gun, whichever may be desired. While I describe and show the invention relating to the detonation system herein in considerable detail for the sake of suificiency of the disclosure of the invention as claimed herein, the subject matter of that detonation system is however claimed in my divisional application (E. M. Deloraine, 23A) Serial No. 586,226, filed April 2, 1945, now abandoned.

The circuit 55 is provided with two connections GI and 62, on opposite sides of the discharge tube 60, the connection 6| being connected toan antenna 65 and the connection 62 being connected to the body 52 of the shell. The antenna as shown in Fig. 2 is arranged in a compact coil and is disposed adjacent an insulating wall 66, the antenna being connected to the circuit 55 by a suitable coupling 61 extending through the insulating wall. The antenna in this form will not provide much radiation effect and is so disposed that when the shell is fired by the gun, it will not be responsive to the detonation impulses so that there will be no danger of untimely bursting of the shell. To extend the antennato its eflective radiation length when, the shell reaches a desired distance from the gun such as indicated by the range line 68 (Fig. 1). I provide a small arming fuse 68 such as illustrated in Fig. 4 and disclosed in my copending applicationSerial No.

388,036 filed April 11, 1941, and now abandoned, for Electrical Detonation System. Other forms of arming fuses,'however, may be used.

The arming fuse 68 may be arranged in any suitable manner and as shown in Fig. 2, disposed compactly adjacent the coiled antenna 85. The end of the shell body 52 may be closed in any known manner. As shown, a cover plate 18 is threadably engaged to the body 52 at II. The threads are such as to be readily sheared upon the detonation of the charge I2 of the arming fuse thereby causing the antenna 85 to be ejected to its effective length and trailed along after the shell.

The arming fuse 68 is timed by a coil 14 associated with the muzzle of the anti-aircraftgun '25. The coil 14 is supplied with a source of current 15 which may be varied b an adjustable resistance 16. The arming fuse 68 is provided with a coil 18 in which an electromotive force is induced proportional to the current flowing in the coil 14, it being assumed that the muzzle velocities of successive shells are substantially the same. The coil 18 of the arming fuse charges a condenser 19 which inturn is adapted to distectlon apparatus. It therefore follows that the addition of one or more antenna streamers, such as the antenna GEtothebOdy of the shellwillso the impulse reflecting capacity of the shell ,that the reflected pulses thereof can be readily detected and observed on the oscillograph of relatively low powered radio detection apparatus.

The other p pose of the antenna 65 is to increase the reception at the shell of energy from the high frequency detonation impulses transmitted by the detection apparatus to a value sufficient to break down the tube 60 and cause detonation of the shell. Thus, by using the antenna 88 with an arming fuse to extend the antenna to its effective radiation length a thousand feet or so before it reaches the target, the shell will not be prematurely detonated by impulses intended for the detonation of an earlier fired shell. The line 69 represents this arming range. Before extension of the antenna 65 the shell is not responsive todetonation impulses.

Where the detection apparatus is of suflicient power to detect a. shell without the aid of a trailing antenna, a detonation circuit such as shown in Fig. 5 may be used. This form of detonation circuit comprises the detonation circuit of the form shown in Fig. 3, that is, the elements 56, 58 and 88 and in addition, a coil 90, an arming key 92, and a pair of condensers 93 and 94. The arming key 82 may be associated with any known arming means now commonly used to close upon charge through a resistance 8| into a condenser 80 of lesser capacity. To avoid the passage of the discharge current from the condenser I9 from traversing the coil 18, a contact key 84 is provided in the coil circuit which opens the circuit, due to its inertia, a very short time after the cannon fires. The breakdown voltage value of the gas filled tube 85 which is connected in series with a fuse'wire 88 embedded in the charge 12 and which are connected across the condenser 80 is of a particular value, which when attained by the discharge from the condenser 18 will cause the'tube to ionize and pass current to the fuse wire 86. It will thus be apparent that the timing of the arming fuse is determined by the resistance 8| and the electromotive force applied to the muzzle coil 14. By varying the current of the coil 14 by the resistance 16, the distance at which the arming fuse will fire after the shell leaves the gun may be determined. This variation of arming fuse detonation, of course, is determined in accordance with the' distance at which the enemy aircraft is from the detection system.

The purpose of the arming fuse in accordance with the form of shell disclosed in Figs. 2 and 3 is two-fold. The reflection pulses received from a projectile such as an anti-aircraft shell will be, for most detection apparatus, so small in amplitude as not to appear easily observable on the oscillographs thereof. This difiiculty may be overcome by. greatly increasing the power of the detection apparatus but to do so is costly and to avoid this additional expense,.I provide the arming antenna 65 whereby the reflection capacity of the. shell is greatly increased by the detonation of the charge 12 of the arming fuse 68. It is known that a single antenna wire one half wavelength long at a distance of 25 miles or so, will provide a reflecting pulse which may be readily observable on the oscillograph of the usual obstacle deactuation of such arming means the circuit of the coil 80. Thus, when the arming fuse actuates the key 92, the circuit will then be responsive to shell detonation impulses. When the transmitter T sends out high frequency impulses the coil circuit being tuned to the frequency of these pulses will build up energy sufficient to exceed the breakdown point of the tube 60 and thereby pas current through the fuse wire 56.

The building up of energy in either of the forms shown in Figs. 3 and- 5 is graphically illustrated in Fig. 6. Since the frequency of the impulses for obstacl detection purposes is inthe order of 60 persecond, the energy of each impulse will dissipate before the next succeeding impulse traverses the circuit and no building up of voltage occurs. The frequency of the impulse transmission for detonation purposes being in the order of 30,000 per second will tend to build up a voltage across the gas discharge tube 60 similarly as indicated by the curve I00 as long as the pulses transmitted are controlled in such a manner as to insure that the successive pulses received add in phase and that in consequence the energy in the tuned circuit builds up as successive pulses are received. This may be done by using a crystal controlled carrier generator at the pulse transmitter. When this build-up reachesa level such as I02, this added voltage to the voltage stored in the condenser 58 will be sufficient to cause the tube 60 to break down and pass current to the fuse wire 56. By way of example, the condenser 58 may be charged to 200 volts and the additional voltage required to break down the tube 88 may be in the order of 2 volts.

Figs. '7 and 8 illustrate the appearance of the reflection pulses on the oscillograph 20. The pulse 30 represents the reflection of a transmitted impulse by the airplane 3! at a distance of 5 miles from the detection apparatus. The pulse 22 is a reference pulse controlled by an operator through manipulation of the timed base control 32. This reference pulse is caused to move along with the .pulse 30 as .the position of the airplane varies with respect to the detection apparatus. The pulse 50 represents the reflections caused by the shell I fired toward the airplane 3|. The pulse 30 travels fairly slow across the screen of the oscillograph while the shell impulse 50 travels at a much faster rate. In accordance with the form of the apparatus shown in Fig. 1, the operator will press the switch 49 at theinstant the shell pulse 50 reaches the position of the aircraft pulse 30. This will'cause a transmission of 'a detonation impulse detonating the shell almost at the instant the switch 49 is closed. This timing, however, may be varied by known delay means in the transmission of the detonation impulse where itis desirable to initiate transmission of detonation impulses before the shell pulse 50 coincides with the aircraft pulse 30. When the shell 5I bursts, the wave front of the pulse 50 will increase in amplitude substantially asindicated in Fig. 7 because of the increased reflection surface of the shell fragments and then disappear. The operator, of course, may vary the timing of the detonation with respect to the aircraft pulse 30 so that successive shells may be caused to burst at various points in the vicinity of the InFig. 8, asecond shell pulse I05 is indicated for the shell I05 (Fig. 1) 'This second pulse I05 is shown to be very small and may be regarded as the indication received prior to the action of the arming fuse 58 (Figs. 2 and 4) Thus, should the arming pulse 68 be set to act when the shell is at a distance of four miles from the gun, the size of the pulse I05 will increase to the size indicated for the pulse 50. The pulse may thereafter be easily detected and followed by the operator.

In Fig. 9, I have shown a semi-automatic apparatus whereby the timing of the shell detonationmay be more accurately controlled. This apparatus may be substituted for the manual switch 49 or it may be used in conjunction therewith, that is, the switch 49 would be connected in parallel with the control shown in Fig. 9. The apparatus of Fig. 9 comprises a reference index I20 which is movable along the time base of the oscillograph 20. Any suitable means may be provided to move the index I20, such as a threaded shaft I2I having a handle I22 to be actuated by the operator. Adjustably coupled to the index I20 at a suitable distance therefrom by a coupling such as turnbuckle I23 is a photo-electric cell I25 which may be focused on the oscillograph by any suitable focusing means. For purposes of illustration, I have shown a light transmitting rod I26, such as Lucite to focus the light of the pulse on the cell I25. The Lucite rod may be suitably shaped to provide a small light receiving end closely adjacent the screen along which the shell pulse indication is adapted to travel. The photoelectric cell is then disposed at the other end of the rod I26 so that when the light pulse passes the light receiving end of the rod. light therefrom is conveyed to actuate the cell I25. The current of the cell I25 may be amplified or as shown, it can be fed directly to the grid I30of a gas discharge tube I3I. This current passed by the cell is adapted to cause a surge flow through the tube I3I to the switching device S to switch the transmitter T over from the frequency source F1 to the frequency source F2.

The Lucite rod I25 is disposed an adjustable distance to one side of the index I20 so that when the shell pulse 50 reaches a position corresponding to the position of the rod I26, the current required to actuate switch S and thereby transmit detonation pulses is caused to operate at an adjustabie time interval before the pulse 50 reaches the pulse 30. Suitable delay means may be provided to vary the distance at which the rod I28 may be disposed with respect to the reference index I20. Such delay timing provides adequate spacing between index I20 and the rod I26 to allow considerable manual adjustment by the operator of the'coupling I23. The operator can thereby vary the timing of the shell detonations with respect to the aircraft as viewed on the oscillograph.

The mechanical index. I20 may be replaced by a pulse such as the reference pulse 22 and the movement of the cell I25 caused to correspond with movement of the pulse 22 by controlling the position of the cell by manipulation of the control 32. Then an adjustment may be provided between the cell and the control 32 to vary .the distance between the focus point of the cell and the reference pulse 22.

Another form of control means, by which the timing of the detonation impulses may be determined is shown in Fig. 10. In this form, two pulse index members I40 and HI are provided, one to be moved to correspond to movement or location of the aircraft pulse and the other the shell pulse. Each of these members is provided with a contact for engagement with a resistance I43. A circuit including the two follower contacts, the resistance I43, an energy source I44, 9. variable resistance I45, and an electromagnetic coil I46 is provided to control the switching device S1. The electromagnetic cofl I46 is adapted to actuate the movable contact I48 of the switch S to switch from the low frequency source Fr to the high frequency source F2 as hereinbefore described. The timing of the switching operation is determined by a predetermined voltage drop obtained by the relative positioning of the index members I40 and I along the resistance I43. The switch S1 preferably has a known snap action including a toggle spring I41 adapted to snap the switch contact arm I49 upon the exertion of a given force by the coil I46. This effective relative positioning of the members I40 and MI may be varied by adjusting the resistance I45.

Operation .as follows: The detection device I0 will be used for scanning the sky for the appearance of any enemy aircraft. that an enemy aircraft 3| appears in the sky, the scanning motor 4| may be de-energized and the position controls 44 and 45 actuated to obtain and maintain the maximum indications of the reflection pulses received from the aircraft 3|. The operation of the controls 44, 45 and 32 will determine the angles of elevation and azimuth and the distance as well as the speed of the aircraft. These measurements are continuously transmitted to the antiaircraft gun 25. When the aircraft comes within range of the gun, the gun is fired, the arming fuse 68 being timed by the adjustment of the resistance I6. when the shell reaches a predetermined level 69 in accordance with the setting of the resistance IS. the arming fuse will act to extend the antenna streamers 55 whereupon the reflection pulse of the shell is clearly observable upon the oscillograph 20. When the shell has nearly reached the distance of the aircraft as indicated on the oscillograph, the operator presses the switch button 49 thereby causing transmission of the detonation impulses to burst the shell. Should the detonation of the shell appear to occur beyond the position of the aircraft, the operator may vary his timing for transmission of the shell detonating impulses and thereby vary the detonation timing of successive shells in the vicinity of the aircraft.

To render the timing of the transmission of detonation impulses, the form of control as shown in Figs. 9 and 10 may be used. These forms eliminate to a large extent the variation in the human element involved and the only manual adjustment required will be the maintenance of the index members I20 or I40, as the case may be, directly opposite the aircraft impulse 30. Then should a variation in shell detonation of successive shells be desired, this may be done by adjusting the coupling I23 or the resistance I depending upon which embodiment has been adopted.

I recognize that many variations in the detection and controlling equipment as well as shell construction and arrangement is possible without departing from this invention. I wish it understood, therefore, that the forms herein shown and described are to be regarded as illustrative of the invention only and not as restricting the appended claims.

What I claim is: k

1. A firing control system comprising a transmitting and receiving station having means to transmit electro-magnetic impulses for obstacle detection purposes, means to receive reflection.

pulses produced in response to said electromagnetic impulses by'obstacles such as aircraft and detonatable projectiles directed at such aircraft, indicator means responsive to pulse energy from the receiving means for producing indications of the relative distance of an'aircraft and a projectile from said station, and detonation control means to effect the transmission from said station of detonating impulses to the projectile providing a comparatively larger amount of energy than that of said obstacle detection impulses when the indications provided by said indicator means show both the aircraft and the projectile at substantially the same distance from said station.

2. The firing control system according to claim 1 wherein the detonation control means comprises a manually operable switch.

3. The firing control system according to claim 1 wherein the detonation control means includes means automatically responsive to the arrival of a projectile pulse at a predetermined distance from the aircraft pulse on said indicator means to eil'ect transmission of the detonation pulses.

. 4. The firing control system according to claim 1 wherein the detonation control means includes means responsive to the arrival of a projectile pulse at a determined relation with respect to the aircraft pulse on said indicator means to eifect transmission of detonation pulses, and means manually adjustable to vary the'relation of the pulses at which said responsive means will operate.

5. The firing control system according to claim 1 wherein the detonation control means includes a pulse index member, said index member being movable by an operator in accordance with movement of the aircraft pulse on said indicator means, means including a photo-electric cell movable in accordance with the arrangement or said index member, and means by which the photo-electric cell will observe the projectile pulse as the latter nears the aircraft pulse, and means responsive to the actuation of said cell by the projectile pulse to effect the transmission of detonation pulses.

6. The firing control system according to claim 1 wherein the detonation control means comprises an aircraft pulse index member, a projectile pulse index member, said members being relatively movable to correspond respectively to the reflection pulses of the selected aircraft and a projectile as indicated on said indicator means, and means responsive to a predetermined relative positioning of said members to efiect the transmission of the detonation pulses.

'7. The firing control system according to claim 1 wherein the detonation control means comprises an aircraft pulse index member, a projectile pulse index member, said members being relatively movable to correspond respectively to the reflection pulses of a selected aircraft and a projectile directed at such aircraft as indicated on said indicator means, a circuit including a source of energy and a resistance, said members having contacts movable along said resistance, switching 'means responsive to a given voltage drop determined by the relative positions of said contacts along said resistance to effect transmission of the detonation pu ses, and a variable resistance to vary the relative positioning of said members at which said switching means will operate.

8. A firing control system comprising obstacle detection means to detect moving obstacles, means including a gun to shoot shells, each shell having arming means and a detonation circuit, said circuit including a fuse, a gas filled tube adapted to pass current through said fuse to detonate said shell when the tube is subjected to a predetermined voltage and an antenna normally retained in compact form in the shell but which when extended is responsive to detonation impulses to supply said predetermined voltage to said tube, means at the gun for setting said arming means into operation by the firing of the-shell to extend said antenna to its effective length after a predetermined lapse of time for response to detonation impulses so that the shell can thereafter be detonated, said detection means including devices operable to indicate at given instances the relative positioning of a selected obstacle and-a shell fired by said gun, and detona tion control means under the control of an opera- I tor to effect transmission of said detonation impulses when the detection means indicate the shell to be in a suitable position relative to the obstacle.

9. A firing control system comprising obstacle detection means, said detection means being operable to detect and indicate moving obstacles by the transmission of energy impulses and the reception of their reflections caused by the presence of target within the range of the detection means, means including a gun to shoot shells according to the detection data, each shell having means including a fuse responsive to impulses of predetermined energy supplying characteristics to detonate the shell, a combined course indicator instrument, including means to indicate the relative positioning at given instances of the reflection pulses of a target and a shell fired at such target, and detonation control means under con- 11 trol not an operator to transmit impulses or said predetermined energy supplying characteristics when the indicator shows the shell to be in the vicinity oi! said target, said detection means including a low frequency impulse generator and a high frequency impulse generator, and the detonation control means being operable to switch from one to the other of the generators so as to transmit low frequency impulses for obstacle detection purposes and high frequency impulses 10 for shell detonation purposes.

' EDMOND M. DELORAINE.

REFERENCES blimp The following references are oi record in the tile 01' this patent: 1

12 UNITED STATES PATENTS Number Number 

